Method of controlling the growth of fungi

ABSTRACT

ORGANOTIN COMPOUNDS, WHICH HAVE THE STRUCTURE   1,2-(-COO-SN(-R)2-OOC-),(X)N-BENZENE   WHEREIN EACH R REPRESENTS PHENYL OR AN ALKYL GROUP HAVING FROM 4 TO 8 CARBON ATOMS; X REPRESENTS ALKALY GROUPS HAVING FROM 1 TO 4 CARBON ATOMS, HALOGEN, PHENYL, CARBOXY, OR NITRO; AND N REPRESENTS AN INTEGER IN THE RANGE OF 1 TO 4, EFFECTIVELY CONTROL THE GROWTH OF FUNGI, AND PARTICULARLY PLANT PATHOGENS, WITHOUT CAUSING APPRECIABLE INJURY TO THE HOST PLANT. AMOUNT THE MOST EFFECTIVE TO THESE FUNGICIDES IS DIBUTYL TIN 3,4-DIMETHYL-6-ISOBUTYLPHTHALATE.

United States Patent 3,595,963 METHOD OF CONTROLLING THE GROWTH OF FUNGIPasquale P. Minieri, Woodside, N.Y., assignor to Tenneco Chemicals, Inc.

No Drawing. Continuation-impart of application Ser. No. 620,293, Mar. 3,1967. This application Apr. 3, 1969, Ser. No. 813,342

Int. Cl. A01n 9/00 U.S. Cl. 424288 6 Claims 10 ABSTRACT OF THEDISCLOSURE Organotin compounds, which have the structure wherein each Rrepresents phenyl or an alkyl group having from 4 to 8 carbon atoms; Xrepresents alkyl groups having from 1 to 4 carbon atoms, halogen,phenyl, car- 0 boxy, or nitro; and n represents an integer in the rangeof 1 to 4, effectively control the growth of fungi, and particularlyplant pathogens, without causing appreciable injury to the host plant.Among the most effective of these fungicides is dibutyl tin3,4-dimethyl-6-isobutylphthalate.

This is a continuation-in-part of my copending application Ser. No.620,293, which was filed on Mar. 3, 1967, now US. Pat. No. 3,454,611.

This invention relates to a method of controlling the growth of fungi.More particularly, it relates to a method of controlling the growth offungi on living plant materials that are intended for human or animalconsumption.

In accordance with this invention, it has been found that certainsubstituted organotin phthalates are highly effective against a widevariety of plant pathogens, in cluding those responsible for earlyblight and late blight of tomatoes, powdery mildew of beans, and otherserious crop diseases. Because they provide long lasting protection,fewer applications of these fungicides are required to control plantdiseases than are necessary when man ganese ethylene bis dithiocarbamateand other previously known agricultural fungicides are used.

The organotin phthalates that can be used in the practice of thisinvention may be represented by the structural formula wherein each Rrepresents phenyl or an alkyl group having from 4 to 8 carbon atoms; Xrepresents an alkyl group having from 1 to 4 carbon atoms, halogenphenyl, carboxyl, or nitro; and n represents an integer in the range of1 to 4. Illustrative of these compounds are the following: di-n-butyltin 3,4,5-trimethylphthalate, di-nhexyl tin 3,5,6-trimethylphthalate,di-2-ethyl-hexyl tin 3,4-dimethyl-6-isobutylphthalate, ditert. butyl tin3,4,5,6- tetrachlorophthalate, di-Z-ethylbutyl tin 4-car-boxyphthalate,di-n-octyl tin 3,4,5,6-tetraphenylphthalate, diphenyl tin3-nitrophthalate, and the like. A single dialkyl (or diaryl) tinphthalate or a mixture of two or more of these compounds may be used.

The fungicidal compounds may be prepared, for example, by the reactionof the appropriate substituted phthalic anhydride with a dialkyl ordiaryl tin oxide or by the reaction of a phthalic acid with a dialkyl ordiaryl tin dichloride. Suitable substituted phthalic anhydrides may beprepared by aromatizing the products of the condensation of maleicanhydride with dienes, such as 1,3-hexadiene, 2,4-hexadiene,3-methyl-2,4-hexadiene, 2,4 dimethyl 1,3 pentadiene, dimethylbutadienes,isoprene, 1,1,3 trimethylbutadiene, 1,1,4 trimethylbutadiene, 1 phenyl 4methylbutadiene, allo ocimene, 5- methyl 4 isopropyl 1,3 hexadiene, andthe like, by treatment first with palladium and then with an alkaline oracidic aqueous solution.

While the fungicidal compounds may be applied as r such to the soil,they are ordinarily and preferably combined with an inert fungicidaladjuvant carrier and applied as a solution, emulsion, suspension, ordust. Aqueous emulsions or suspensions that contain about 0.001 percentto 1 percent by weight, and preferably 0.01 percent to 0.5 percent byweight, of the active agent are particularly suitable for this use.These compositions may also contain about 0.01 percent to 0.1 percent byweight of a wetting agent, such as an alkyl sulfate, an alkyl arylsulfonate, a sulfosuccinate, a polyethylene glycol ether, and the like.Alternatively, the fungicidal compounds may be dissolved in an organicsolvent, such as acetone, naphtha, ethylene chloride, or kerosene, andapplied as solutions, or they may be mixed with or deposited upon suchfinely-divided solid carriers as clay, chalk, bentonite, talc, kaolin,fullers earth, and the like and applied as dusts.

The fungicidal compounds may be applied by known techniques to plants,to plant seeds, or to the soil in which plants are growing or are to begrown. They may be applied to the parts of the plants above or in thesoil, or the plant seeds may be contacted with the fungicidal compound.Alternatively, the fungicide may be introduced into the soil near theroots of the plants or applied to the surface of the soil and then mixedinto the soil to the desired depth.

The amount of the fungicidal composition that is applied is dependentupon such factors as the species of plant being treated and the plantpathogen whose control is desired and is that amount which will inhibitor prevent the growth of the plant pathogen while causing little or noinjury to the plants. About 1 pound to 200 pounds of the active compoundis ordinarily applied per acre with particularly good results beingobtained when 5 pounds to 35 pounds per acre is used.

The substituted tin phthalates may be used as the sole active componentof the fungicidal compositions. If desired, however, these compositionsmay also contain other fungicides, such as sulfur and the metaldimethyldithiocarbamates; insecticides, such as DDT and benzenehexachloride; or plant nutrients, such as urea, ammonium nitrate, andpotash.

The invention is further illustrated by the examples that follow.

EXAMPLE 1 (A) To 476 grams (3.5 moles) of freshly-distilled alloocimenewas added a solution of 245 grams (2.5 moles) of maleic anhydride in 720grams (8.17 moles) of ethyl acetate at such a rate that the temperaturerose to 88 90 C. and remained at that temperature throughout theaddition. The reaction mixture was heated with stirring at 88-90 C. forhours and then heated under vacuum to remove the ethyl acetate. Theresidue was distilled under reduced pressure to remove unreactedalloocimene from the product. There was obtained about 450 grams of3,4-dimethyl-6-isobutenyltetrahydrophthalic anhydride.

(B) A mixture of 330 grams (1.42 moles) of3,4-dimethyl-6-isobutenyltetrahydrophthalic anhydride and grams of 5%palladium on carbon was stirred for 6 hours at 260280 C. and then cooledto room temperature. After it had been allowed to stand overnight, thereaction mixture was treated with 820 ml. of a 15% aqueous sodiumhydroxide solution, heated at 90100 C. for 1 hour, diluted with 1700 ml.of water, and filtered. The filtrate was acidified to pH 5 withhydrochloric acid. The crude product that precipitated was collected andrecrystallized from ethanol. There was obtained 102.6 grams of3,4-dimethyl-6-isobutylphthalic anhydride, which melted at 8990 C.

(C) A mixture of 195 grams (0.782 mole) of di-nbutyl tin oxide, 182grams (0.782 mole) of 3,4-dimethyl- 6-isobutylphthalic anhydride, and1170 ml. of toluene was heated at its reflux temperature for 3 hours andthen cooled to room temperature. The reaction mixture was heated to 60C. under vacuum to remove the toluene. There was obtained 377 grams ofdi-n-butyl tin 3,4- dimethyl-6-isobutylphthalate, which contained 24.8percent Sn (calculated, 24.7 percent Sn).

EXAMPLE 2 (A) A solution of 0.3 mole of 3,4-dimethylphthalic anhydrideand 0.6 mole of potassium hydroxide in 300 ml. of water was heated on aWater bath to distill off the water. There was obtained 0.3 mole of thedipotassium salt of 3,4-dimethylphthalic anhydride.

(B) A mixture of 0.1 mole of the dipotassium salt, 0.1 mole of diphenyltin dichloride, and 400 ml. of ethanol was heated at its refluxtemperature for 5 hours, cooled to room temperature, and stirred at roomtemperature overnight. The reaction mixture was filtered, and the solidproduct was dried at 125 C. There was obtained a high yield of diphenyltin 3,4-dimethylphthalate.

EXAMPLE 3 A mixture of 18.1 grams (0.05 mole) of di-n-octyl tin oxide,11.6 grams (0.05 mole) of 3,4-dimethyl-6-isobutylphthalic anhydride, and150 ml. of toluene was heated at its reflux temperature for 3 hours andthen cooled to room temperature. The reaction mixture was heated to 80C. under vacuum to remove the toluene. There was obtained 28.9 grams ofdi-n-octyl tin 3,4-dimethyl-6-isobutylphthalate, which contained 20.97percent Sn (calculated for C H O Sn, 20.05 percent Sn).

EXAMPLE 4 A mixture of 12.5 grams (0.05 mole) of dibutyl tin oxide and150 ml. of toluene was heated to its reflux temperature to remove tracesof water azeotropically and then cooled to room temperature.Tetraphenylphthalic anhydride (22.6 grams; 0.05 mole) was added, and thereaction mixture was heated at its reflux temperature for two hours.Upon removal of the toluene by distillation under vacuum, there wasobtained 35.2 grams of di-nbutyl tin tetraphenylphthalate, which meltedat 223 225 C. and which contained 16.64 percent Sn (calculated for C H OSn, 16.95 percent Sn).

4 EXAMPLE 5 Using the procedure described in Example 4, 3-nitro phthalicanhydride was reacted with di-n-butyl tin oxide to form di-n-butyl tin3-nitrophthalate in a substantially quantitative yield. The productmelted at 145 -147 C. and contained 27.4 percent Sn and 3.20 percent N(calculated for C H NO Sn, 26.9 percent Sn and 3.17 percent N).

EXAMPLE 6 Using the procedure described in Example 4, trimelliticanhydride was reacted with di-n-butyl tin oxide to give an 88.9 percentyield of di-n-butyl tin 4-carboxyphthalate, which melted at 237-240 C.and which contained 28.8 percent Sn (calculated for C H O Sn, 28.7percent Sn).

EXAMPLE 7 Using the procedure described in Example 4, tetrachlo-1'ophthalic anhydride was reacted with di-n-butyl tin oxide in tolueneto form di-n-butyl tin 3,4,5,6-tetrachlorophthalate in a substantiallyquantitative yield. The product Sn and 18.7 percent Cl (calculated for CH Cl O Sn, 22.2 percent Sn and 26.6 percent Cl).

EXAMPLE 8 (A) Acetone solutions were prepared by dissolving 100 mg.portions of the products of Examples 1-7 in 10 ml. of acetone thatcontained 2000 p.p.m. of sorbitan trioleate (Span and 5000 p.p.m.'of apolyoxyethylene ether of sorbitan monooleate (Tween 80). The acetonesolutions were dispersed in ml. portions of distilled water to formaqueous solutions that contained 1000 p.p.m. of the fungicidal compound.More dilute solutions were prepared by adding distilled water to thesesolutions.

(B) Fifty percent water-soluble fungicidal powders were prepared byblending 2 grams of the products of this invention with 1.88 grams ofattapulgite clay, 0.06 gram of sodium alkyl naphthalenesulfonate (NekalBX-78), and 0.06 gram of sodium lignosulfonate.

EXAMPLE 9 Series of experiments were carried out in which tomato plantswhich had been sprayed with dilute aqueous solutions of di-n-butyl tin3,4-dimethyl-fi-isobutylphthalate or the commercial fungicide Maneb(manganous ethylene bis dithiocarbamate) prepared by the procedure ofExample 8A were sprayed with suspensions of spores of the fungi thatcause early and late blight of tomatoes. One week after treatment, thedegree of suppression of the disease was noted. From the results givenin Table I it will be seen that di-n-butyl tin3,4-dimethyl-6-isobutylphthalate was more effective than Maneb incontrolling both early blight and late blight of tomatoes.

Separate lots of sterile soil that had been inoculated with a plantpathogen were planted with seeds of a crop plant. The planted soil wasthen treated with a dilute aqueous solution of di-n-butyl tin3,4-dimethyl-6-isobutylphthalate or Maneb prepared by the procedure ofExample 8A. Two weeks after treatment the results were noted. Theresults of these tests are given in Table II.

TABLE II fiat? of Percent a a 1 n f Plant pathogen Plant Fungicide zpfpmg.) ghi h 500 97 I 100 92 Di-n-butyl tin3,4-d1mcthyl-6-1sobutylphthalate 20 90 4 Colletotrz'chum ZagmariumCucumber 500 188 100 100 Maueb 20 98 4 80 500 99 v 100 99 Di-n-butyl tin3,4-d1methyl-G-lsobutylphthalate 20 99 4 84 0.8 81 500 100 100 100C'ercospora bctzcola Sugar beet Di-n-butyl tin3,4dunethyl-Gisobutylphthalate l 20 89 4 87 0. 8 37 500 100 100 100Maneb 20 90 4 61 0. 8

After2 of artificial rainfall.

EXAMPLE 11 A series of experiments was carried out in which tomatoplants that had been treated with the aqueous solutions of thefungicidal powders of Example 8B were sprayed with a suspension ofspores of Alternaria solani, the fungus that causes early blight oftomatoes. One week after treatment, the degree of suppression of thedisease was noted. The results obtained are summarized in Table III.

TABLE III Percent control Rate of of early application blight ofFungicide (p.p.m.) tomato Product of Ex;

EXAMPLE 12 Tendergreen bean plants with fully expanded primary leaveswere inoculated with spores of Erysiphe polygoni, the powdery mildewfungus. Forty-eight hours later, the plants were sprayed with aqueoussolutions prepared by the process of Example 8A. After a period of 7-10days, the degree of suppression of the disease was noted. The resultsobtained are summarized in Table IV.

The terms and expressions that have been used are used as terms ofdescription and not of limitation. There is no intention in the use ofsuch terms and expressions of excluding any equivalents of the featuresshown and described or portions thereof. It is recognized that variousmodifications are possible within the scope of the invention claimed.

What is claimed is:

1. The method of protecting living plants from attack by fungi whichcomprises applying to the plants a fungicidal amount of an organotincompound having the structural formula wherein each R represents amember selected from the group consisting of phenyl and alkyl groupshaving from 4 to 8 carbon atoms; X represents a member selected from thegroup consisting of alkyl groups having from 1 to 4 carbon atoms,halogen, phenyl, carboxy, and nitro; and n represents an integer in therange of 1 to 4.

2. The method of claim 1 wherein the organotin compound is di-n-butyltin 3,4-dimethyl-6-isobutylphathalate.

3. The method of claim 1 wherein the organotin compound is di-n-butyltin 3,4,5 ,-6-tetrachlorophthalate.

4. The method of claim 1 wherein the organotin compound is di-n-butyltin 3,4,5,6-tetraphenylphthalate.

5. The method of claim 1 wherein the organotin compound is di-n-butyltin 4-carboxyphthalate.

6. The method of claim 1 wherein the organotin compound is di-n-buty1tin 3-nitrophthalate.

ALBERT T. MEYERS, Primary Examiner F. E. WADDELL, Assistant Examiner

